Abstract of Darwin’s theory

There are two extant versions of the abstract of Darwin’s theory of natural selection. One was sent to Asa Gray on 5 September 1857, enclosed with a letter of the same date (see Correspondence vol. 6, letter to Asa Gray, 5 September [1857] and enclosure). It is in the hand of Ebenezer Norman, Darwin’s copyist and includes minor alterations and corrections by Darwin. The letter and enclosure are in Gray’s correspondence in the Gray Herbarium of Harvard University.

The other version is the draft from which the fair copy for Gray was made. It was retained by Darwin (DAR 6). This version was subsequently sent to Charles Lyell and Joseph Dalton Hooker in June 1858 as part of Darwin’s contribution to the Darwin–Wallace paper read on 1 July 1858 at the Linnean Society of London (see letters to Charles Lyell, 18 [June 1858], [25 June 1858], and 26 [June 1858]; letters to J. D. Hooker, [29 June 1858] and [29 June 1858]; and letter from Charles Lyell and J. D. Hooker to the Linnean Society, 30 June 1858). Since the draft differs in some respects from the copy sent to Gray and also forms the basis of the printed version published in the Journal of the Proceedings of the Linnean Society (Zoology) 3 (1859): 45–62, it has been transcribed here. The transcript does not record Darwin’s corrections and alterations except where they are substantial. Differences between Darwin’s manuscript and the printed text of Darwin and Wallace 1858 have been noted. For CD’s work on the proof-sheets of the paper, see letter from J. D. Hooker, 13–15 July 1858, and letter to J. D. Hooker, 21 July [1858].

(1)1 It is wonderful what the principle of Selection by Man, that is the picking out of individuals with any desired quality, & breeding from them, & again picking out, can do. Even Breeders have been astonished2 at their own results. They can act on differences inappreciable to an uneducated eye. Selection has been methodically followed in Europe for only the last half century. But it has occasionally & even in some degree methodically been followed3 in the most ancient times. There must have been, also, a kind of unconscious selection from the most ancient times,4 namely in the preservation of the individual animals (without any thought of their offspring) most useful to each race of man in his particular circumstances. The “roguing”, as nurserymen call the destroying of varieties, which depart from their type is a kind of selection. I am convinced that intentional & occasional selection has been the main agent in making5 our domestic races. But, however, this may be, its great power of modification has been indisputably shown in latetimes.6 Selection acts only by the accumulation of very7 slight or greater variations, caused by external conditions, or by the mere fact that in generation the child is not absolutely similar to its parent. Man by this power of accumulating variations adapts living beings to his wants,—may be said8 to make the wool of one sheep good for carpet & another for cloth &c.9

(2.) Now suppose there was a being, who did not judge by mere external appearance, but could10 study the whole internal organization—who never was capricious,—11 who should go on selecting for one end12 during millions of generations, who will say what he might not effect! In nature we have some slight variation, occasionally in all parts: & I think it can be shown that changed conditions of existence is the main cause of the child not exactly resembling its parents; & in nature geology shows us what changes have taken place & are taking place. We have almost unlimited time: no one but a practical geologist can fully appreciate this: think of the Glacial period, during the whole of which the same species of shells at least13 have existed: there must have been during this period, millions on millions of generations.

(3) I think it can be shown that there is such an unerring power at work on14 natural selection (the title of my Book), which selects exclusively for the good of each organic being. The elder Decandolle, W. Herbert, & Lyell have written strongly15 on the struggle for life; but even they have not written strongly enough. Reflect that every being (even the Elephant) breeds at such a rate, that in a few years, at most a few centuries or thousands of years16 the surface of the earth would hold the progeny of any one species.17 I have found it hard constantly to bear in mind that the increase of every single species is checked during some part of its life, or during some shortly recurrent generation. Only a few of those annually born can live to propagate their kind. What a trifling difference must often determine which shall survive & which perish.—

(4) Now take the case of a country undergoing some change: this will tend to cause some of its inhabitants to vary slightly; not but what18 I believe most beings vary at all times enough for selection to act on.19 Some of its inhabitants will be exterminated, & the remainder will be exposed to the mutual action of a different set of inhabitants,—which I believe to be more20important to the life of each being than mere climate. Considering the infinitely various ways, beings have to obtain food by struggling with other beings,21 to escape danger at various times of life, to have their eggs or seeds disseminated &c &c, I cannot doubt that during millions of generations individuals of a species will be born22 with some slight variation profitable to some part of its economy: such23 will have a better chance of surviving, propagating this variation, which will be slowly increased by the accumulative action of natural selection; and the variety24thus formed will either coexist with or more commonly will exterminate its parent form. An organic being like the woodpecker or missletoe may thus come to be adapted to a score of contingencies25 : natural selection, accumulating those slight variations in all parts of its structure, which are in any way useful to it, during any part of its life.

(5) Multiform difficulties will occur to everyone on this theory.26 Most27 can, I think, be satisfactorily answered.— “Natura non facit saltum”28 answers some of the most obvious.— The slowness of the change & only a very few undergoing29 change at any one time answers others. The extreme imperfection of our geological records answers others.—

(6.) One other principle,30 which may be called the principle of divergence plays, I believe, an important part in the origin of species. The same spot will support more life if occupied by very diverse forms: we see this in the many generic forms in a square yard of turf—31 or in the plants & insects on any little uniform islet belonging almost to as many genera & families as to species.—32 We can understand this with the higher animals, whose habits we best understand.33 We know that it has been experimentally shown that a plot of land will yield a greater weight if cropped with several species of grasses than with 2 or 3 species.34 Now every single35 organic being, by propagating so rapidly, may be said to be striving its utmost to increase in numbers. So it will be with the offspring of any species after it has broken into36varieties or sub-species or true species. And it follows, I think, from the foregoing facts, that the varying offspring of each species will try (only few will succeed) to seize on as many & as diverse places in the economy of nature, as possible. Each new variety or species, when formed will generally take the place of & so37 exterminate its less well-fitted parent. This, I believe, to be the origin of the classification or arrangement of all organic beings38 at all times. These39always seem to branch & sub-branch like a tree40 from a common trunk; the flourishing41twigs destroying the less vigorous,—the dead & lost branches rudely representing extinct genera & families.—

This sketch is most imperfect; but in so short a space I cannot make it better. Your imagination must fill up very wide blanks.— Without some reflexion it will appear all rubbish; perhaps it will appear so after reflexion.— C. D.42

Provenance: CUL DAR 6: 51

Notes

1 The printed version is headed: “Abstract of a Letter from C. Darwin, Esq., to Prof. Asa Gray, Boston, U.S., dated Down, September 5th, 1857.” (Darwin and Wallace 1858, p. 50). The text comprises the second part of the joint contribution. The section numbers are enclosed in square brackets in the manuscript.

9 The printed version reads: ‘good for carpets, of another for cloth, &c.’ (Darwin and Wallace 1858, p. 51).

10 The printed version reads: ‘there were a being who did not judge by mere external appearances, but who could’ (Darwin and Wallace 1858, p. 51).

11 The manuscript includes a passage at this point that was deleted by CD. It reads: ‘& who selected not for his own good, but for that of the being on which he was acting—suppose he went on selecting’.

12 The printed version reads: ‘and should go on selecting for one object’ (Darwin and Wallace 1858, p. 51).

13 The printed version reads: ‘the same species at least of shells’ (Darwin and Wallace 1858, p. 51).

16 The phrase ‘or thousands of years’ does not occur in the printed version, which reads: ‘in a few years, or at most a few centuries’ (Darwin and Wallace 1858, p. 51).

17 At this point in the manuscript there is a note in pencil that reads: ‘the progeny of any one species wd. cover the surface of the earth’. The printed version reads: ‘the surface of the earth would not hold the progeny of one pair’ (Darwin and Wallace 1858, p. 51).

19 The printed version reads: ‘to act on them’ (Darwin and Wallace 1858, p. 52). In the manuscript the passage ‘this will . . . act on’ was inserted by CD above a deleted passage that reads ‘& not freely open to immigration. Its inhabitants will be exposed to new conditions;’.

24 The printed version reads: ‘and of propagating their new and slightly different structure; and the modification may be slowly increased by the accumulative action of natural selection to any profitable extent. The variety’ (Darwin and Wallace 1858, p. 52).

42 In June 1858, when the abstract was sent to Hooker, the final sentence was deleted in pencil by CD and a note added, also in pencil: ‘This was sent about 9 months ago, but I daresay I can get Date’. The signature was changed from ‘C.D.’ to ‘C. Darwin’. See letter to J. D. Hooker, [29 June 1858]. The verso of the final page was marked twice by Darwin in pencil: ‘Sketch sent to Dr Asa Gray.—’ There is a further note, in ink, that reads: ‘This was sent to A. Gray 8 or 9 months ago, I think October 1857 [‘or perhaps’ del]’. The printed version concludes with the signature ‘C. DARWIN.’

Encloses MS by A. R. Wallace. CD has been forestalled. " . . . if Wallace had my MS sketch written out in 1842 he could not have made a better short abstract!" Wallace does not say if he wishes CD to publish MS, but CD will offer to send it to journal.

Everything in Wallace’s sketch also appears in CD’s sketch of 1844. A year ago CD sent a short sketch of his views to Asa Gray. Can CD honourably publish his sketch now that Wallace has sent outline of his views? "I would far rather burn my whole book than that he or any man shd. think that I had behaved in a paltry spirit." Does not believe Wallace originated his views from anything CD wrote to him.

Communicate papers by CD and A. R. Wallace on "The Laws which affect the Production of Varieties, Races, and Species". Explain that CD and Wallace have, independently and unknown to each other, arrived at the same theory to account for the appearance and perpetuation of specific forms, and that neither has yet published, although CD first sketched his theory in 1839. Give their reasons for arranging the joint presentation.

Sends proofs [of "On the tendency of species to form varieties … ", read 1 July 1858,Collected papers2: 3–19]. CD could publish his abstract [later theOrigin] as a separate supplemental number of [Journal of the Linnean Society].

JDH has studied in detail CD’s manuscript on variable species in large and small genera and concurs with its consequences. Discusses methodological idiosyncrasies of systematists, e.g., Bentham, Robert Brown, and C. C. Babington, which complicate CD’s tabulations.